From 668ac2fdae69ed358ecf690d6a07428e5a9ee2f7 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Tue, 16 Nov 2010 21:02:37 +0000
Subject: [PATCH] Split pseudo-instruction expansion into a separate pass, to
 make it easier to debug, and to avoid complications when the CFG changes in
 the middle of the instruction selection process.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119382 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/CodeGen/Passes.h             |  4 ++
 include/llvm/InitializePasses.h           |  1 +
 lib/CodeGen/ExpandPseudos.cpp             | 84 +++++++++++++++++++++++
 lib/CodeGen/LLVMTargetMachine.cpp         |  3 +
 lib/CodeGen/SelectionDAG/InstrEmitter.cpp | 13 ----
 5 files changed, 92 insertions(+), 13 deletions(-)
 create mode 100644 lib/CodeGen/ExpandPseudos.cpp

diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h
index bbedabd4077..7345f15dd1c 100644
--- a/include/llvm/CodeGen/Passes.h
+++ b/include/llvm/CodeGen/Passes.h
@@ -213,6 +213,10 @@ namespace llvm {
   /// addressing.
   FunctionPass *createLocalStackSlotAllocationPass();
 
+  /// createExpandPseudosPass - This pass expands pseudo-instructions.
+  ///
+  FunctionPass *createExpandPseudosPass();
+
 } // End llvm namespace
 
 #endif
diff --git a/include/llvm/InitializePasses.h b/include/llvm/InitializePasses.h
index 50443e2f3fe..23f918797db 100644
--- a/include/llvm/InitializePasses.h
+++ b/include/llvm/InitializePasses.h
@@ -92,6 +92,7 @@ void initializeDomViewerPass(PassRegistry&);
 void initializeDominanceFrontierPass(PassRegistry&);
 void initializeDominatorTreePass(PassRegistry&);
 void initializeEdgeProfilerPass(PassRegistry&);
+void initializeExpandPseudosPass(PassRegistry&);
 void initializeFindUsedTypesPass(PassRegistry&);
 void initializeFunctionAttrsPass(PassRegistry&);
 void initializeGCModuleInfoPass(PassRegistry&);
diff --git a/lib/CodeGen/ExpandPseudos.cpp b/lib/CodeGen/ExpandPseudos.cpp
new file mode 100644
index 00000000000..4f9e8ad2ae0
--- /dev/null
+++ b/lib/CodeGen/ExpandPseudos.cpp
@@ -0,0 +1,84 @@
+//===-- llvm/CodeGen/ExpandPseudos.cpp --------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Expand Psuedo-instructions produced by ISel. These is usually to allow
+// the expansion to contain control flow, such as a conditional move
+// implemented with a conditional branch and a phi, or an atomic operation
+// implemented with a loop.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "expand-pseudos"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+
+namespace {
+  class ExpandPseudos : public MachineFunctionPass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    ExpandPseudos() : MachineFunctionPass(ID) {}
+
+  private:
+    virtual bool runOnMachineFunction(MachineFunction &MF);
+
+    const char *getPassName() const {
+      return "Expand CodeGen Pseudo-instructions";
+    }
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+  };
+} // end anonymous namespace
+
+char ExpandPseudos::ID = 0;
+INITIALIZE_PASS_BEGIN(ExpandPseudos, "expand-pseudos",
+                "Expand CodeGen Psueod-instructions", false, false)
+INITIALIZE_PASS_END(ExpandPseudos, "expand-pseudos",
+                "Expand CodeGen Psueod-instructions", false, false)
+
+FunctionPass *llvm::createExpandPseudosPass() {
+  return new ExpandPseudos();
+}
+
+bool ExpandPseudos::runOnMachineFunction(MachineFunction &MF) {
+  bool Changed = false;
+  const TargetLowering *TLI = MF.getTarget().getTargetLowering();
+
+  // Iterate through each instruction in the function, looking for pseudos.
+  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
+    MachineBasicBlock *MBB = I;
+    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
+         MBBI != MBBE; ) {
+      MachineInstr *MI = MBBI++;
+
+      // If MI is a pseudo, expand it.
+      const TargetInstrDesc &TID = MI->getDesc();
+      if (TID.usesCustomInsertionHook()) {
+        Changed = true;
+        MachineBasicBlock *NewMBB =
+          TLI->EmitInstrWithCustomInserter(MI, MBB);
+        // The expansion may involve new basic blocks.
+        if (NewMBB != MBB) {
+          MBB = NewMBB;
+          I = NewMBB;
+          MBBI = NewMBB->begin();
+          MBBE = NewMBB->end();
+        }
+      }
+    }
+  }
+
+  return Changed;
+}
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 3ba1b89a802..d19b319884e 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -345,6 +345,9 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM,
   // Print the instruction selected machine code...
   printAndVerify(PM, "After Instruction Selection");
 
+  // Expand pseudo-instructions emitted by isel.
+  PM.add(createExpandPseudosPass());
+
   // Optimize PHIs before DCE: removing dead PHI cycles may make more
   // instructions dead.
   if (OptLevel != CodeGenOpt::None)
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 61c2a90e7ed..1445abed2ee 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -721,19 +721,6 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
   // hook knows where in the block to insert the replacement code.
   MBB->insert(InsertPos, MI);
 
-  if (II.usesCustomInsertionHook()) {
-    // Insert this instruction into the basic block using a target
-    // specific inserter which may returns a new basic block.
-    bool AtEnd = InsertPos == MBB->end();
-    MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
-    if (NewMBB != MBB) {
-      if (AtEnd)
-        InsertPos = NewMBB->end();
-      MBB = NewMBB;
-    }
-    return;
-  }
-  
   // Additional results must be an physical register def.
   if (HasPhysRegOuts) {
     for (unsigned i = II.getNumDefs(); i < NumResults; ++i) {